Amplifying system



Dec. 1, 1931.

w. H. T. HOLDEN AMPLI'FYING SYSTEM Filed Nov. 19, 1925 INVENTOR WEZ'HMQZW ATTORNEY F battery or batteries being employed for or the grids of Patented Dec. 1, i931 WILLIAM H. irynionnrm, or moox m; semi-m mos rofhiirmrcali. i i

PHONE AND TELEGRAPH en agemen or mw y nx A licationnlea mie ter 19;1925'.; ser a1 No. 70,157.- v

This invention relates to -amplifying systems, and more particularly-toarrangements in such systems includinga' plurality of vacuum' tubes interconnecting an, incoming cir-' cuit and an outgoing circuit .so that the circuits associated with said vacuum tubes are energized by a source of; alternating current. It has been the practice tocconnect a plu rality of vacuum tubesin tandelnwithr'ef-i spect to each other for'amplifying a band of frequencies in such a waythat a plurality of batteri-es known as A, 137, :and fc l'bate teries were associated with the circuits of the vacuum tubes for their energization, the FA? battery or batteries being employed for bri'ng ing the cathodes of the vacuum tubes to the proper state of incandescence, the fB? battery vor batteries being employed for bringing the plates ofthe vacuum tubes to suitablepotentials with respect to said cathodes, and-the providing the necessary bias I said vacuum tubes. Where two or more tubes were operated at'the same plate potentialsia single .B battery "was connected to these plates through a lead common to said plates. The presence of the impedance of this lead and of the B battery common tothe plate circuits ofthe several tubes tended to give rise tothe phenomenon known as singing,

which generally interferred with the faithful reproduction of signals.& 7 v

It is therefore an object of this inventioni to provide arrangements'for eliminating the use of the ,A,-B and C batteries for establishing the necessary operating characteristics for a plurality of vacuumtubes, and to provide instead arrangements suitable for connecting a source of alternating current to the vacuum tubes for accomplishing the same ends. L I i It 1s another Ob]t of-th s nvention to connect a plurality of res stances 1n series relationship with a source of electromotive force, one resistance being included in the input circuit and another resistance being ine cluded in the output circuit of eachsvacuum tube, so that'the drop in potential across each resistance will be ofpthe roper'magnitude to energizethe associate circuit a a fit 1's; atria use of thisjinveiition -ito provide arrangementsforrectifying a source 7 0t alternating current insuchaway that the rectifiedmurrent; may be employed-for set;- tlng up a difference in potential acrosskeach Of plurality of resistances which are lasso of inventioniistlie ciatedswith a plurality of vacuum-tubes so,

provision of; means for rectifying altern atv Q ing. currents andionpassing the rectifiedilt t t o g a ser circ i lu in the output circuit and filamentof a'vacu ifwbe, and? sist n e wh ch is 5 ciated with the, input circuit ofthe vacuum tubeiso that theldrop in potential across the resistance is 10f. ay ma-gnitude sufficient to tial withrespect totfhefilament of the vacu-m l 1 bring. the I grid suitable negative potenum tube. 1

1 il d na redthemat c W111 pointed out with particularity in the appended claims, theinvention, itself,both as to its I bi 'i t endw i es l beb t e u de stood ,from the description hereinafter following when readin: connection with the accompanying drawing 1 showing one .embodi ment of the invention I a 7 V a n 1 Referring to the drawing, there is shown an; em fy s st m having an i c m n a circuit connected to the leads vl and an outgoing circuit connected to the leads 2'. 'lransformers 3and 4 are employed for, in

terconnecting the incoming, circuit: connected to leads 1 andthe outgoing circuit connected toleads 2 of the system by means of a lu I rality of vacuum tubes "so arranged as to mamplify a band of frequencies. ,Vacuum tubes 5', 6, 7 and8 are connected in tandem with respect to each other between the trans formers l3 andrt, and thesevacuum tubesare w inductively coupled by inductances 9,10 and 11. It will be understood thatthese vacuum tubes may be coupled by resistances, by transformers; or by any other means well "known in theart. "A potentiometer 34: is associated with the input circuit ofthervacuum" tube 5 for regulating the inputpvoltage fromutrans former 3 to the grid of the vacuum tube 5,

b thereby controlling the gain of the amplifier.

f A source of alternating current, prefer- I ably a 110 volt 60 cycle house lighting circuit,

transformer 14 by closing a switch 15;

is designated by the reference character 12, and this vsource of alternating current is connected with the primary winding 13 o jfjha e secondary ofthetransfohner 1a comprises three windings 16,17 18 being low voltag'ewindings,and'windings '17 being a high voltage winding. 'The-ref- V erence character 19 represents a rect fier which is of the electron type having an anode and a cathode, but it will be understood that any other rectifier Well known in the art may 1 be employed instead thereof.- 1 ,11"he,-winding 16-of the transformer lt is 'us'ed to heat thecathodeof the'va'cuum tube 8,

and the winding- 18 is .used for heating the cathode *of the rectifier 19, Thus-the 'last stageofaniplification in the amplifying sys temis supplied with alternatingcurrent for furnishing Lthe'energy for the cathode of the vacuum tube thereof. It will be understood that it is oneofthe-features of this invention to heat thecathodes of the tubes of the last stages of amplification inan-amplifyin'g systern by alternating current, because by confining the use'of alternating current to the cathodes ofthe last stages of amplification, the noise produced in the ampifier output due to theuse of alternating current-to heat; the

cathodes is practically negligible.

' A plurality of resistances are connected; series relationship with each other, one i'n the input circuit and another in the'output cir' cuitof each vacuum tube-employed in the amplifying system, 'Thus t-he resistance20i is associated with the input circuit and resist ance 21 is associated withthe output 'ci'rcuit of the-vacuum tube 5. Resistance 22is a es:

ci ated with the input circuit andfresistan'ce 23 isassoc-iatedwith the-output circuit of' the vacuumtube 6, The resistance 24 is asso ciated with the input circuit,"a'nd the resist ance 25' is associated withtheoutput circuit ofthe-vacuurn tube 7', and the resistance 26 4 is associated with the input; circuit of-the vacuum tube 8. Resistancesmayormay not bec'on'nec't'ed in shuntwitlrthe cathodes of thevacuunitubes, 'such resistances being em ployed onlyin cases" in which too much cur rent would otherwise flow therethrough; If, by virtue of'the size,-the diameter andthe material employed for the cathode, it would receive too much current, resistances be arranged toshunt such cathodes, as shown in this case by the reference characters 27fand A filter 29, preferably a 'low pass filter, is

' connected with the rectifier 19 for rendering the'series circuit connected to the rectifier as '7 freefrom'alternating current components as possible. This filter29. includes inducand' 18, winding @lfti and tance and a pair of condensers. A rheostat 30 is also included in the series circuit connected to the rectifier 19 for regulating the rate offlow of current from the rectifier 19 through the resistances 20 to 28 and filaments 5 to 7 inclusive. Theoutp'ut circuit of the vacuum' tube 8 includes theanode and the cathode of the vacuum tube 8, the primary winding of the transformer 4,; a condenser 31, the cone;

ductor'j 32' connected to; the midpoint-of the low voltage secondary windingtlb, and the outer conductors 33 connected'to the terminals of tli'elow voltage secondary winding 16. I

v{El e terminals of the secondary winding 17 I s set up a high potential alternating current which is-rectified'and then employed for energizing the resistances 20-to 28 inclusive.

through the-leads connected tothe outer te'ra min'als of theisecondarywinding 18 tothe 'midpoint of said winding-and then'through' theinductance of the filter 29' to the regulat ingarm ofthe rheostat 3O." There are in se-V 'ries with the r'esistance of the rhecstat, the

resistance S 26 and 25, the cathode of the vacuum tube 7, resista1'1ce's'24 and 23, the resistance 28 whichshuntsthe cathode of the vac-i uu'rn tube 6', the resistances 22 and 21, the resistance' '27 which shunts the cathode of the vacuum tube 5,"and the resistance 20. From ;the left-hand terminal of the resistance 20, the circuit to the leftFhand terminal ofthe point of the secondary winding 16. Thus the current flowing through-the resistances 20'to During one-half of the cycle,the: right-hand terminal ofethe winding 17 becomes-positive,

and the left-hand terminal becomesflnegative. Thus, a positive potential is impressed on th'e anode'of the rectifier 19 so that rectification may take place. :The current then flows 28', inclusive, is the sum of the currentsfflowv in g through the resistance "of therheostat 30 and through the output circuit of the vacuum tube8. The condenser 31 is alsoconnected inj th'ejoutput circuit of. the vacuum tube 8 for by-passing alternating currents i The 'ciit off frequency ofthejfilter 29 is lower than the frequency of the source of alternating current 12 and may be, for exai'n'ple,30cycles; Since nofrequency present in the 60 cyc'le s'ourc'e or produced therefrom by the action of the rectifier 19 is below the cut-off frequency of the filter 29, the series circuit connected between the rectifier 19and the resistances 20 to 28 willbe substantially free from alternatingcurrentcomponents.-

The resistances 20 to 28, inclusive,are of such rnagnitudes thatthe difference in poten issaaca p J3 tial across each of said resistances is sufficient for providing the proper potential for itsassociated circuit. Thus the drops 1n potential across the terminals of the resistances and 21 are suflicientto supply proper voltages to the grid and plate circuits, respec tively, of the vacuum tube 5, the drops in potential across the terminals of tie resistances 22 and 23 are suificient to supply proper voltages to the grid and plate circuits, respectively, of the vacuum tube 6, the drops in potential across the terminals of resistances 24 and 25 are sufficient to supply the proper voltages to the grid and plate circuits, g

put circuit thereof, someofthe filaments oi .thevaquumgti bes:being. eatedihy of the vacuum tube 7, and the drop in potential across the'terminals of the resistance 26 is suflicient to supply the proper voltage to the grid circuit of the vacuum tube 8; The" resistances 27 and 28 are of magnitudes sufiicient to divert enough of thecurrentfrom' the cathodes of vacuum .tubes 5 and 6, respectively; so that said cathodes may be brought to the properstate of incandescence. I

It is withinthe scope of this inventionto relate a plurality of resistances to a plurahty of vacuum tubes, some of the resistances be-,

ing associated with the input circuits, and

other of the resistances being associated with,

the output circuits of the vacuum tubes, all

being in series relationship with each other with respect to a source of rectified current,

so that the'circuits of the vacuum tubes will be properly energized thereby;

While the invention has been disclosed in a particular embodiment, which is deemed desirable, it is to be understood that it is capable of embodiment in other and widely vathe appended claims.

l/Vhat is claimed is 1. An amplifier comprising a plurality of three-electrode vacuum tubes each having an input circuit and an output circuit, a source of alternating current, a rectifier, and a plu- -ality of resistances arranged in pairs between the filaments of said vacuum tubes and in series relationship with said-filaments and said rectifier, the drop in potential across said resistances being utilized to supply the operating potentials for the input and output circuits of said vacuum tubes.

2. An amplifier comprising a plurality of vacuum tubes each having an anode, a cathode, and a control electrode, each tube having an input circuit including the cathode and the control electrode and an output circuit including the cathode and the anode, a

source of alternating current, a rectifier, and

a plurality of resistances arranged in series relationship with the cathodes of said vacuum tubes, two resistances being apportioned for each vacuum tube, the two resistances apportioned for any one vacuum tube being different from those apportioned for any of each vacuum tube,

' lrrenth ng.arran e lmserie ha o her' vacu m; tubes, cm ea hmin 9i. said-,re istane I-he ng in udedii be inputir uia and th ether in h i cuttut circuit of u hmagnit de that-the Tdrgp. i pe entiel crqss the terminals .th raet will b sufficie'nt resista ce-bein o energize th ei cui associated therewith r a v a l a i ampl fiee a sume of alte natin urrent, a rec ifier aipl na ity-ct th a 51cc:

trade v cuu t be In serie :re atiqnshipnith sa -hatt r. a plurality Qf 'esistancea1tware; ista'nci a being ..a's ociated 5 5.1 1 uum. tube, one being-ar ange th input circuit and th athe tierrangedz n itheicut Wi h said; rasis neeaandsaid r p i ip te a ns di sta Q a tq;bili n ;theprep r Peent a it the circuitsa e 'atedx therew th-1 e- A:1. y tem1 for ema ring a t rna in currentsq milr si gesplliia a rave e Y tr de awum tubes; a plural an resis hwacuum. tube iharingi nainputs i resis ances and npu inc udi g me 19 e; t Pi cir uit a 1- aesthetic? M deast? ances, the two, resistances associated w th one aevau mwb s ,ba-nguiaeaa sea those associated with any of the other vacuum map ., a ross sa r istance be i tubes, a source of potential, and means for sending current from said source of potential through said resistances, the drop in potential across each of said resistances being of a magnitude suitable to be supplied tothe circuit associated therewith.

incoming and outgoing circuits comprising a plurality ofthree-electrode vacuum tubes arranged in tandem with respect to each other,

the anode of one vacuum tube being directly' connectedtothe control electrode of the coils each. in common with the output circuitof one vacuum tube and the input circuit of the succeeding vacuum tube, a plurality of resistances, one resistance being associated. with the input circuit-of a vacuum tube i and. another resistance bein associated with the output circuit thereo and a source of potential, all of said resistances being in seriesrelationship with said source of poten-.,

'6. In combination, a plurality of three electrode discharge tubes, a plurality of re sistances, one of said resistances being arsucceeding vacuum tube, a plurality of choke ranged in the input circuit of each ofsaid f 5. In combination, an incoming circuit, an v out oin circuit means interconnectin said f p f mamas discharge tubes 7 and another 1 of said -resist ancesfbingarrapged inqthebutput Circuit .0f' eachffsaid di'schargetubes, thetw o' '*re-' sis/games associated," respe'cti velyywith 'the' input and: output;-cil cuitsofjanymne of the I discharge-tubes bing distinct from those resistsinces associated with any Of the' otherdis V harg ti1be,- anfd asolirce' (jfrp'dtential arranged; ih -"seri esrelationship"with said' le sistances, *sai 1 circuits bein supplied with suitable potentials by virtue of the drops in r V potentialdilq'to said resistances, said dis- 7 V chargeftubes" being atfidifierent potentials" with respect-to.on tei'minal of said."so'ur'ce7'v of potential. I Tljlemethodof'qperafiihg a plurality Q'f vfa uum tub es having a plurality 1 0f ;r"esist 1 ah cfesf h ssQciatedthere-with, dfie rsis tanbe bei 1 ing in-jthe input circuit and -another resist ahcebihgd-nfithe putput' circuit of each- Yac- V 1mm tub thetwoiesistances assqciatdwith 'alifywo'lle of the vacuum tub's' b e'ing; "different fnom 'thosefaisso'ciated with any .ofthe other Vacuum tubes, whichpohsibs intran's mittin'g a5 direct-current through said resistaiic es sazthat'thefiropin potential acrossthe terminals of-eagih (if; said resistances will" be suffici'enfltoenergize=the associated ci'muit.' In testimony wherof, I have signed 'my name f0" ihi's' specification this" 18th day of okr'nibeg l'msg; a V, 7 fl i I ILL -fY L ass I 

